on these topics, and regularly provided assessments to the Home Fleet and other commands. The decision to attack the Bodø area was made on the basis of Ultra intelligence obtained by decoding German radio signals, from which the Allies learned that the ships in the region included the large oil tanker , which was carrying fuel for the German battle group at Altafjord. In addition, at the time of Operation Leader two groups of Norwegian Secret Intelligence Service (SIS) agents operated radio transmitters on the coast of Helgeland: "Crux III" on the island of Renga and "Pisces" on Lurøy. Both groups provided reports to the Allies on the weather and shipping movements in the target area in the lead-up to the attack. From 3 October onwards, "Crux III" radioed weather reports every half hour. Attack The Home Fleet sailed from Scapa Flow on 2 October 1943. The British elements of the force were the battleships (Fraser's flagship) and , the light cruiser and seven destroyers. The US Navy component comprised Ranger, Tuscaloosa and four destroyers. The Allied ships were not detected by German forces during their voyage north, and arrived at the flying-off position for Rangers air wing approximately off Bodø shortly before dawn on 4 October. The US Navy attack force was organised into two groups of aircraft: the Northern Attack Group, which was to strike shipping at Bodø, and the Southern Attack Group, which was to target ships near the town of Sandnessjøen nearly to the south. Both groups had one Norwegian navigator from No. 333 Squadron RAF in the lead aircraft, providing knowledge of the local geography. The Northern Attack Group, which comprised 20 Dauntless dive bombers escorted by eight Wildcat fighters, began to take off at 6:18 am. These aircraft flew at low altitude towards Bodø until their crews sighted Myken Lighthouse, and then turned to the north and climbed as they neared the target area. Weather conditions were clear, and the air crews had good visibility. Four Dauntlesses and a pair of Wildcats were detached from the force shortly after it passed Myken Lighthouse to search for German shipping near Åmøya island. They soon sighted the German freighter , and two of the dive bombers attacked the ship. The Americans believed that La Plata was badly damaged, and the six aircraft rejoined the main body of the Northern Attack Group. In the meantime the other